(a) Field of the Invention
The present invention relates to a retrofocus type wide-angle lens system to be used in micro readers, micro printers, facsimiles, etc.
(b) Description of the Prior Art
Lens systems to be used in micro readers, micro printers, facsimiles, etc. must be so designed as to afford an aperture efficiency of 100% for assuring uniform intensity of illumination over the entire range of image. However, all the conventionally known retrofocus type lens systems comprising six lens components of six elements are designed as those for photographic cameras and, therefore, have aperture efficiencies on the order of 40%.about.60%. There are available no retrofucus type lens systems which are designed for an aperture ratio of F/2.8, field angle on the order of 63.degree. and an aperture efficiency of 100%. Further, from the viewpoint of correction of aberrations, lens systems for photographic cameras are different from those for micro reader, micro printer, facsimile, etc. since the former lens systems are designed for correction of aberrations for photographing object placed at indefinite distance, whereas the latter systems are designed for photographing object at finite distance.